The invention provides an amphiphilic siloxane-containing vinylic monomer which comprises one sole ethylenically unsaturated group and a siloxane-containing group covalently linked to the ethylenically-unsaturated group through a hydrophilic linker. The present invention is also related to a polymer, an actinically-crosslinkable silicone-containing prepolymer, a silicone hydrogel polymeric material, or a silicone hydrogel contact lens, which comprises monomeric units derived from an amphiphilic siloxane-containing vinylic monomer of the invention. In addition, the invention provides a method for making silicone hydrogel contact lenses using a water-based lens-forming formulation comprising an amphiphilic siloxane-containing vinylic monomer of the invention and/or an actinically-crosslinkable silicone-containing prepolymer of the invention.